Risco relativo e extensão de perda de biodiversidade na bacia do rio Pandeiros, tributário do rio São Francisco

Abstract

Identifying the changes caused by human activities in aquatic ecosystems and understanding how they affect biodiversity are fundamental steps for managing the São Francisco River basin. The objective of this study was to evaluate the extent and relative risk of stressors for benthic macroinvertebrate biodiversity. 40 streams belonging to the Pandeiros River basin were sampled, using a spatially balanced and probabilistic methodology, to select sections that were representative of the most varied conditions in the basin. The risk to macroinvertebrate communities is 1.7 times greater in places where anthropogenic disturbance is greater (IDI) in relation to areas of lesser disturbance, and this stressor is present in 24.5% of the basin's extension. The fine substrate stressor is present in 29% of the entire basin, and represents a 1.21 times greater risk for biodiversity in sites where this substrate predominates, in relation to sites less impacted by fine substrate. Disturbances in the riparian zone also pose a 1.5x greater risk to communities and are present in 21% of the river basin. The presence of pasture in the riparian zone of the streams is 40%, and presented a 1.05x greater risk for macroinvertebrate communities. Therefore, local actions aimed at disturbances that potentially pose a risk to biodiversity must be a priority in the management of the São Francisco River basin and its tributaries.